1. Field of the Invention
The present invention relates to an antenna device suitably applied to, for example, a portable telephone terminal or the like and a portable transceiver provided with this antenna device.
2. Description of the Related Art
Conventionally, as an antenna mounted in such a portable transceiver as a portable telephone terminal or the like, there is an antenna referred to as a helical antenna besides a so-called rod-shaped whip antenna. This helical antenna is an antenna configured by winding a wire in a coil shape and it can be built in an interior of the terminal. A helical antenna built in a conventional portable terminal has a configuration shown in FIG. 1, for example.
FIG. 1 is a cross-sectional view showing an interior of an upper portion of a portable terminal, and a terminal 1 configured by a predetermined casing is built-in at its upper portion with a speaker 2 for conversation and is built-in with a circuit board 3 assembled with a communication circuit for performing transmission processing and reception processing. Shield cases 4, 5 are disposed on both faces of the circuit board 3, so that the communication circuit assembled on the circuit board 3 is shielded from the outside. Also, one end of a helical antenna 6 formed by winding an electrically conductive wire in a coil shape is connected to an upper end portion of the circuit board 3 and the connected portion of the upper end portion is used as a power feed portion.
This helical antenna 6 has a winding direction extending upwardly, and it is configured as an antenna extending in a direction parallel to a plane of the circuit board 3.
In this conventional helical antenna, as shown in FIG. 1, since an open end side of the antenna approaches to the head h of a user of the portable terminal when this terminal is used, there is a problem that the antenna is apt to be affected by the human head and the characteristics of the antenna deteriorate, so that an excellent radio communication environment can not be obtained.
Also, when there is a ground pattern which is a ground potential portion in the vicinity of an antenna mounting portion of the circuit board where the helical antenna is mounted, the characteristics of the antenna remarkably deteriorate. Accordingly, the ground pattern can not be provided in the vicinity of the portion on which the antenna has been mounted, and therefore a circuit can not be assembled near the portion where the antenna is mounted. As a result, the occupancy area of the antenna-mounted portion on the area of the board becomes large, which results in prevention of reduction in size of a portable terminal.
Furthermore, as shown in FIG. 1, when the wire configuring the helical antenna is mounted on the circuit board, there has been a problem that the working efficiency for mounting thereof is poor. That is, helical antennas are generally fixed at their end portions to circuit boards by soldering or the like, and it is necessary to fix the helical antennas in a state where they are always oriented to a constant direction. However, there is a problem that, as the wires having a three-dimensional configuration such as the helical antenna are always fixed in the same state by soldering or the like, the working efficiency is not good.
An object of the present invention is to improve wireless characteristics of a transceiver using a helical antenna and a working efficiency at a time of mounting an antenna.
According to an aspect of the present invention there is provided an antenna device which comprises a helical antenna composed of a conductive wire having a predetermined length one end portion of which is attached to one side face of a circuit board, the other portion of which is wound spirally, and an extending direction of which by the winding is perpendicular to a plane of the circuit board.
According to the present invention, a direction in which the wire configuring an antenna is wound to extend becomes a direction perpendicular to the plane of the circuit board. When a transceiver equipped with this antenna is used, the open end side of the antenna can be oriented in a direction in which the antenna goes away from the head of a user.